Modelling electromagnetic properties

of chiral composite materials :Daniel’s contribution

Bruyères-le-Châtel, 8 décembre 2015

Frédéric MARIOTTEDirecteur Adjoint

CEA/DCS

First Gogny Conference

What is the chirality ?

An objet is called chiral if it cannot be superimposed on its mirror image by translations or rotations

The name chiral originates from the Greek “Kheir”, which means « hand ».

What is the statement of the problem ?

Develop new radar absorbing materials.

Use the bianistropic properties of chiral media :In the frequency domain, such media could be described by three complex parameters e, m et g.

Develop models to predict the performance of chiral composite (conductive chiral inclusions in non-chiral host medium) :1. Compute the field scattered by a

single chiral inclusion.

2. Calculate the average properties of the isotropic chiral material.

Daniel’s approach : analytical calculation

Describe interactions between an electromagnetic wave and a single chiral inclusion (canonical helix : a loop with 2 wires).

Numerical models.

Simplified analytical models (dipole approximation).

Full analytical method : Daniel's approach. Calculation of the scattered field based on an analytical solution to the integral equation for the surface current Js(r’) on the canonical helix (model applicable without any limitations of the particle dimensions with respect to the wavelength).

with a analytical description of the Green Function Ga et Gb

Numerical Calculations

Validation of the model by measurements

Chiral composite modeling

Calculate the constitutive parameters of a chiral composite with perfectly conducting randomly oriented helixes in a lossy matrix).

Use of Maxwell-Garnett model for dilute distributions of inclusions.

Daniel’s approach : calculation of the interaction between helices, but again using analytical models ……

Daniel’s scientific impact Daniel Gogny was mentor of PhD students, post doc, visiting scientists, …

All those studies, directed by Daniel Gogny, permitted to establish very fruitful scientific cooperation with :• the electrical engineering department of University of Pennsylvania (headed by

Nader Engheta), • the electromagnetic laboratory of University of Illinois (directed by Raj Mittra), • electrical and computer engineering department of the University of Arizona

Tucson (Richard Ziolkowski),• the Technical University of Saint-Petersburg (Sergei Tretyakov),• …

We organized together in may 1994, the 3rd International Workshop on Chiral, Bi-isotropic and Bi-anisotropic Media, Chiral'94 in Périgueux (France). He was co chairman of the scientific program with Fedor Fedorov (scientific academy of Belorussia).

Daniel supported and promoted submissions of scientific publications in journals with an international committee of readers, to serve as reviewer of scientific papers, …

Frédéric MariotteDirection centrale de la sécuritéDirecteur Adjoint

Commissariat à l’énergie atomique et aux énergies alternativesCentre de Fontenay-aux-Roses | 92265 Fontenay-aux-Roses CedexT. +33 (0)1 46 54 72 77| F. +33 (0)1 46 54 83 43

Etablissement public à caractère industriel et commercial | RCS Paris B 775 685 019

CEA

| PAGE 9

Thank you Daniel